In the field of computer radiography (CR) an image is produced for medical purposes of an object, for example a patient or a body part of the patient, by means of X-ray radiation which is stored in a storage phosphor layer as a latent X-ray image. In order to read out the image information stored in the storage phosphor layer, the storage phosphor layer is stimulated by means of an irradiation device. As a result of this stimulation the storage phosphor layer emits emission radiation which has an intensity corresponding to the quantity of image information on the X-ray image stored in the storage phosphor layer. The emission radiation emitted by the storage phosphor layer is collected by a detector and converted into electrical signals which contain an image of the image information. The electrical signals are processed further, and the image information stored in the storage phosphor layer is then made visible. The image information can be displayed directly on a monitor, for example, or be written onto a photographic X-ray film by means of a printer used specifically for X-ray images.
An apparatus for reading out X-ray information stored in storage phosphor plates is known from US 2006/0131525 A1. This apparatus includes an input unit for inputting a number of cassettes which can be stacked one behind the other and with storage phosphor plates which are to be read out, and an output unit provided next to the input unit for outputting cassettes. A read-out unit is located within the apparatus beneath the output unit. In order to read out the storage phosphor plates located within the cassettes the cassettes input into the input unit are pushed into the output unit. Here the storage phosphor plate located within the respective cassette is removed from the latter and conveyed downwards into the read-out unit in order to be read out. The storage phosphor plate which has been read out is then conveyed back into the cassette and moved forwards with the latter within the output unit in order to make space for the next cassette to be read out.
With this apparatus the storage phosphor plate located within a subsequent cassette can only be read out in the read-out unit once the previous cassette which has already been read out has first of all been fully removed from the input region of the read-out unit located within the output unit, and the subsequent cassette has then been moved on from the input unit to the output unit. This can lead to undesired delays when processing individual cassettes or larger stacks of cassettes.
A further apparatus for reading out X-ray information stored in storage phosphor plates is known from US 2006/0131526 A1. With this apparatus the read-out unit is disposed between the input unit and the output unit. The cassettes are moved from the input unit horizontally towards the read-out unit. Here the storage phosphor plate located within the respective cassette is moved downwards to within the apparatus, is read out and moved back into the cassette which is finally moved from the read-out unit horizontally towards the output unit.